Method of making a shaped silicon carbide-silicon matrix composite and articles made thereby

Abstract

A method is described for making a shaped silicon carbide-silicon matrix composite. A confined carbon fiber preform is infiltrated with sufficient molten silicon metal at a temperature in the range of from about 1400° C. to about 1800° C. in an inert atmosphere or vacuum.

What I claim as new and desire to secure by Letters Patent of the United States is: 
     
       1. A method for making a silicon-carbide ceramic within 1/2% tolerance of the desired shape which comprises, (1) infiltrating molten silicon at a temperature of from 1400° C. to 1800° C., into a shaped carbon-fiber part while it is substantially contained in a mold in a non-oxidizing atmosphere and under reduced pressure, and   (2) separating the resulting silicon-carbide ceramic from the mold where the carbon fiber used in (1) has a specific gravity in the range of from about 1.3 to 1.5.   
     
     
       2. A method in accordance with claim 1, where the mold is treated with boron nitride prior to the infiltration of the molten silicon. 
     
     
       3. A method in accordance with claim 1, where the infiltration of the molen silicon is accomplished under a pressure of from 1 × 10 -2  torr to 3 torr. 
     
     
       4. A method in accordance with claim 1, where the carbon fiber structure is in the form of carbon felt. 
     
     
       5. A method in accordance with claim 1, where the carbon fiber structure is in the form of a carbon fiber cloth. 
     
     
       6. A method in accordance with claim 1, where the carbon fiber structure is in the form of a carbon fiber preform made from carbon fiber tow. 
     
     
       7. A method for making silicon carbide ceramic within 1/2% tolerance of the shape desired which comprises (1) employing a carbon fiber wick to effect the infiltration of molten silicon at a temperature of from 1400° C. to 1800° C. into a mold substantially filled with a material comprising carbon fibers in a non-oxidizing atmosphere and under reduced pressure and   (2) separating the resulting silicon carbide ceramic from the mold where the carbon fibers used in (1) have a specific gravity in the range of about 1.3 to 1.5.   
     
     
       8. A method in accordance with claim 7, where the material comprising carbon fibers is a preformed shaped structure.